Describe the issue or problem
In a plugin, I want to get information about the currently displayed issue. When I call one of the public member functions of the Issue object, I get a fatal PHP error. Why? What is wrong?
Steps I took leading up to the issue
I have stripped down my plugin to the bare minimum. I use the following register function:
public function register($category, $path, $mainContextId = NULL) {
// Register the plugin even when it is not enabled
$success = parent::register($category, $path, $mainContextId);
if ($success && $this->getEnabled($mainContextId)) {
HookRegistry::register('Templates::Common::Footer::PageFooter', array(&$this, 'addSpecialIssueArticles'));
}
return $success;
}
The function “addSpecialIssueArticles” is as follows:
function addSpecialIssueArticles($hookName, $params) {
$templateMgr =& $params[1];
$output =& $params[2];
$issue = $templateMgr->get_template_vars('issue');
echo("<pre>");
var_dump($issue);
echo("</pre>");
$descr = $issue->getLocalizedDescription();
}
The last line generates a fatal PHP error:
[13-Sep-2023 09:07:19 UTC] PHP Fatal error: Uncaught Error: Call to a member function getLocalizedDescription() on null in /var/www/html/ojs_test_3.3.0-14/plugins/generic/specialIssueTST/SpecialIssueTST.i
nc.php:37
Stack trace:
#0 /var/www/html/ojs_test_3.3.0-14/lib/pkp/classes/plugins/HookRegistry.inc.php(107): SpecialIssueTSTPlugin->addSpecialIssueArticles('Templates::Comm...', Array)
#1 /var/www/html/ojs_test_3.3.0-14/lib/pkp/classes/template/PKPTemplateManager.inc.php(1527): HookRegistry::call('Templates::Comm...', Array)
#2 /var/www/html/ojs_test_3.3.0-14/cache/t_compile/25bcbc63bc70e004505931d447fb4131f159a9b2^4dffb64063bb972c37e05619a2ccd9d0ea7473ac_0.app.frontendcomponentsfooter..php(70): PKPTemplateManager->smartyCallH
ook(Array, Object(Smarty_Internal_Template))
#3 /var/www/html/ojs_test_3.3.0-14/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_template_resource_base.php(123): content_64637002a791a1_09056910(Object(Smarty_Internal_Template))
#4 /var/www/html/ojs_test_3.3.0-14/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_templa in /var/www/html/ojs_test_3.3.0-14/plugins/generic/specialIssueTST/SpecialIssueTST.inc.php on line 37
What application are you using?
I am using OJS 3.3.0.14
Additional information
The var_dump produces the following output:
object(Issue)#255 (6) {
["_data"]=>
array(16) {
["id"]=>
int(22)
["journalId"]=>
int(1)
["volume"]=>
int(7)
["number"]=>
string(1) "1"
["year"]=>
int(2020)
["published"]=>
int(1)
["current"]=>
int(1)
["datePublished"]=>
string(19) "2020-03-09 14:20:04"
["lastModified"]=>
string(19) "2020-03-09 14:20:04"
["accessStatus"]=>
int(1)
["showVolume"]=>
int(1)
["showNumber"]=>
int(1)
["showYear"]=>
int(1)
["showTitle"]=>
int(0)
["description"]=>
array(1) {
["en_US"]=>
string(0) ""
}
["title"]=>
array(1) {
["en_US"]=>
string(0) ""
}
}
["_hasLoadableAdapters"]=>
bool(false)
["_metadataExtractionAdapters"]=>
array(0) {
}
["_extractionAdaptersLoaded"]=>
bool(false)
["_metadataInjectionAdapters"]=>
array(0) {
}
["_injectionAdaptersLoaded"]=>
bool(false)
}